FWIW, I installed a custom cooler similar to Modshack's. I now have the whirring, whining noise that everyone is describing. See my thread at:
New Engine Noise post-Oil Cooler Install
I've made a couple videos to document the sound. I wouldn't blame Stillen for this one. It's either a natural tendancy for the sandwich plates or a plate-maker issue (Mocal in my case). However, my cooler works great. I suppose my only concern is the oil pressure then, which I can't measure currently.